The present invention relates generally to the completion of oil and gas wells. More specifically, the present invention relates to a retrievable well packer assembly adapted to form a seal between a production tubing string and a surrounding well casing at a subsurface location within an oil or gas well.
U.S. Pat. No. 3,391,740 describes a retrievable well packer which is set by the fluid pressure applied through the tubing string from the well surface. In the patented assembly, the application of pressure causes an annular resilient seal assembly to expand radially into sealing engagement with the surrounding well casing, and thereafter, to radially expand metal anchoring dogs or "slips" into a secure frictional engagement with the well casing to prevent longitudinal displacement of the well packer. The assembly includes upper and lower spreading cones which are moved toward each other during the setting procedure to force the slip elements radially outwardly. Tapered locking segments, having friction teeth formed along their radially inner surfaces, are wedged behind the lower spreader cone assembly to hold the packer in its set position after the setting pressure is released. Retrieval of the packer is effected by pulling upwardly on the tubing string causing a shear pin to sever so that the spreader cones may be separated to permit the seal assembly and slip assembly to retract away from the surrounding casing.